Packaged surface acoustic wave devices

ABSTRACT

Packaged surface acoustic wave devices are provided. The packaged surface acoustic wave devices are relatively thin and can have a height of less than 220 micrometers. The packaged surface acoustic wave device includes a photosensitive resin over a conductive structure which may be formed by a plating process. The conductive structure may overlie a cavity-defining structure encapsulating a surface acoustic wave device, the cavity-defining structure including walls and a roof. The photosensitive resin can include a phenol resin. The photosensitive resin can be relatively thin. Edge portions of a piezoelectric substrate can be free from the photosensitive resin.

CROSS REFERENCE TO PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 C.F.R. § 1.57.This application claims the benefit of priority under 35 U.S.C. § 119(e)of U.S. Provisional Application No. 62/725,133, filed Aug. 30, 2018 andentitled “PACKAGED SURFACE ACOUSTIC WAVE DEVICES,” the disclosure ofwhich is hereby incorporated by reference in its entirety.

BACKGROUND Technical Field

Embodiments of this disclosure relate to packaged surface acoustic wavedevices.

Description of Related Technology

A surface acoustic wave filter can include a plurality of surfaceacoustic wave resonators arranged to filter a radio frequency signal.Each resonator can include a surface acoustic wave device. Surfaceacoustic wave filters can be implemented in radio frequency electronicsystems. For instance, filters in a radio frequency front end of amobile phone can include surface acoustic wave filters. A plurality ofacoustic wave filters can be arranged as a multiplexer. For example, twosurface acoustic wave filters can be arranged as a duplexer.

Surface acoustic wave devices can be enclosed within a package toprotect the surface acoustic wave devices. The package can add to thesize of a packaged surface acoustic wave device. There is a desire forsmaller and thinner packaged surface acoustic wave devices.

SUMMARY OF CERTAIN INVENTIVE ASPECTS

The innovations described in the claims each have several aspects, nosingle one of which is solely responsible for its desirable attributes.Without limiting the scope of the claims, some prominent features ofthis disclosure will now be briefly described.

One aspect of this disclosure is a packaged surface acoustic wavedevice. The packaged surface acoustic wave device includes a cavity roofover an interdigital transducer electrode of a surface acoustic wavedevice, a conductive structure over the cavity roof, and aphotosensitive buffer coat layer over the conductive structure, thepackaged surface acoustic wave device having a height of 220 micrometersor less.

The packaged surface acoustic wave device can have a height of 200micrometers or less. The photosensitive buffer coat layer can have aheight of 15 micrometers or less.

The packaged surface acoustic wave device can further include apiezoelectric substrate having a first side on which the interdigitaltransducer electrode is disposed, and a cavity wall on the first side ofthe piezoelectric substrate and supporting the cavity roof. An edgeportion of the first side of the piezoelectric substrate can be freefrom the photosensitive buffer coat layer.

The packaged surface acoustic wave device can further include apiezoelectric substrate having a first side and a second side oppositethe first side, the interdigital transducer electrode being on the firstside, and a marking extending into the second side, the markingextending 1 micrometer or less into the piezoelectric substrate. Thepackaged surface acoustic wave device of claim 1 can further include aterminal in physical contact with the conductive structure though anopening in the photosensitive buffer coat layer.

The photosensitive buffer coat layer can include phenol resin. Thephotosensitive buffer coat layer can have a negative photosensitivity.

The surface acoustic wave device can include a plurality of surfaceacoustic wave resonators configured to filter a radio frequency signal.

Another aspect of this disclosure is a packaged surface acoustic wavedevice that includes a cavity structure supported by a die andcooperating the die to encapsulate an interdigital transducer electrodeof a surface acoustic wave device, a conductive structure extending overa portion of an outer surface of the cavity structure, and a insulatinglayer extending over the conductive structure, a portion of theinsulating layer overlying a portion of the conductive structure havinga thickness of less than 15 micrometers.

The cavity structure can include a cavity wall supported by a firstsurface of the die and a cavity roof extending over the interdigitaltransducer electrode and supported by the cavity wall. The packagedsurface acoustic wave device can further include a plurality ofterminals, each of the terminals extending through a portion of theinsulating layer and contacting a portion of the conductive structure.

The insulating layer can include a photoresist material. The insulatinglayer can include a negative photoresist.

The die can include a laser-marked piezoelectric substrate having afirst side and a second side, the first side supporting the cavitystructure, the second side of the laser-marked piezoelectric substratehaving a laser-marked section.

Another aspect of this disclosure is a packaged surface acoustic wavedevice that includes a piezoelectric substrate, a packaging structuresupported by a first surface of the piezoelectric substrate and defininga cavity, the packaging structure including an outer layer includingphotosensitive resin, and a plurality of interdigital transducerelectrodes supported by the piezoelectric substrate and located withinthe cavity.

The packaging structure can include a cavity roof and a cavity wall, thecavity roof and the cavity wall both located between a portion of theouter layer and the plurality of interdigital transducer electrodes.

The packaging structure can include a conductive structure in electricalcommunication with at least one of the plurality of interdigitaltransducer electrodes. The packaging structure can include at least oneterminal overlying a portion of the outer layer and extending through aportion of the outer layer to contact the conductive structure.

Another aspect of this disclosure is a method of manufacturing apackaged surface acoustic wave device, the method including forming aphotosensitive resin over a conductive structure, a portion of theconductive structure located over a cavity roof over an interdigitaltransducer electrode of the surface acoustic wave device, and forming aconductive terminal in contact with the conductive structure, at least aportion of the conductive terminal extending through an apertureextending through the photosensitive resin.

The method can additionally include exposing portions of thephotosensitive resin to light to develop portions of the photosensitiveresin and removing unexposed portions of the photosensitive resin. Themethod can additionally include curing the photosensitive resin afterremoving unexposed portions of the photosensitive resin. Exposingportions of the photosensitive resin to light can include masking aportion of the photosensitive resin extending over a portion of theconductive structure to form the aperture extending through thephotosensitive resin.

Forming the terminal can additionally include forming a conductive layerextending over the aperture extending through the photosensitive resin.The aperture can extend through a portion of the photosensitive resinhaving a thickness of 15 micrometers or less.

The photosensitive resin can include phenol resin. The photosensitiveresin can have a negative photosensitivity.

The can additionally include laser marking a piezoelectric substrate onwhich the interdigital transducer electrode is disposed.

The packaged surface acoustic wave device can have a height of less than220 micrometers.

Another aspect of this disclosure is a method of manufacturing apackaged surface acoustic wave device, the method including forming acavity structure encapsulating interdigital transducer electrodes of asurface acoustic wave device, the interdigital transducer electrodessupported by a piezoelectric substrate, forming a conductive structureextending over portions of an outer surface of the cavity structure, andforming a photoresist layer over the conductive structure, a portion ofthe photoresist layer extending over a portion of the conductivestructure having a thickness of less than 15 micrometers.

The method can additionally include patterning the photoresist layer toform a photoresist buffer coat extending over the conductive structureand the cavity structure and curing the photoresist layer. Thephotoresist buffer coat can include a sidewall portion in contact withthe piezoelectric substrate and circumscribing the cavity structure. Aportion of the conductive structure can be in contact with thepiezoelectric substrate.

Forming the photoresist layer over the conductive structure can includeusing a spin-on process to planarize the photoresist layer. The methodcan additionally include removing portions of the photoresist layerwithin 10 micrometers of the edge of the die.

Another aspect of this disclosure is a method of manufacturing apackaged surface acoustic wave device, the method including forming acavity structure extending over interdigital transducer electrodes ofthe surface acoustic wave device, and forming a conductive structureextending over portions of an outer surface of the cavity structure, andforming a photosensitive resin layer over the conductive structure, aportion of the photosensitive resin layer having an aperture extendingtherethrough and exposing a portion of the conductive structure.

Forming the conductive structure can include depositing a seed layerover the cavity structure and plating the conductive structure onto theseed layer. Forming the conductive structure further can include maskingportions of the seed layer prior to plating the conductive structureonto the seed layer.

The conductive structure can include a gap extending through a portionthereof and exposing a portion of the cavity structure, and thephotosensitive resin layer can fill the gap. The method can additionallyinclude forming a conductive terminal extending through an aperture inthe photosensitive resin layer and in electrical communication with theconductive structure.

Another aspect of this disclosure is a packaged surface acoustic wavedevice that includes a piezoelectric substrate having a first side and asecond side, an interdigital transducer electrode encapsulated within apackage structure and supported by the first side of the piezoelectricsubstrate, and a marking formed in the second side of the piezoelectricsubstrate.

The marking can extend less than 1 micrometer into the second side ofthe piezoelectric substrate. The marking can extend into less than 1% ofa thickness of the piezoelectric substrate. The marking can be formed bya laser.

The piezoelectric substrate can include lithium niobate. Thepiezoelectric substrate can include lithium tantalite.

The package structure can include a cavity structure encapsulating theinterdigital transducer electrode and an outer coat including aphotosensitive resin. A total thickness of the packaged surface acousticwave device can be less than 220 micrometers.

The package structure can include a photosensitive resin buffer coat.The photosensitive resin buffer coat can include phenol resin. Thephotosensitive resin buffer coat can include a negative photoresist. Thepackaged surface acoustic wave device can additionally include aplurality of terminals extending through apertures in the photosensitiveresin buffer coat.

Another aspect of this disclosure is a packaged surface acoustic wavedevice that includes a laser-marked piezoelectric substrate having afirst side and a second side, the second side of the laser-markedpiezoelectric substrate having a laser-marked section, an interdigitaltransducer electrode supported by the first side of the laser markedpiezoelectric substrate, and a structure supported by the first side ofthe laser-marked piezoelectric substrate defining a cavity enclosing theinterdigital transducer electrode.

The laser-marked section can have been exposed to a deep ultravioletlaser. The laser-marked section can include laser markings extendingless than 1 micrometer into the second side of the piezoelectricsubstrate.

The laser-marked piezoelectric substrate can include lithium niobate.The laser-marked piezoelectric substrate can include lithium tantalite.

The package structure can include a photosensitive resin buffer coat.The photosensitive resin buffer coat can include phenol resin. Thephotosensitive resin buffer coat can include a negative photoresist.Another aspect of this disclosure is a method of marking a packagedsurface acoustic wave device, the method including grinding a back sideof a piezoelectric substrate, the back side being opposite a front sideof the piezoelectric substrate on which an interdigital transducerelectrode of the surface acoustic wave device is disposed, and lasermarking the piezoelectric substrate.

The laser marking can form a marking that extends less than 1 microninto the piezoelectric substrate. The laser marking includes can includea wavelength of laser light that allows the piezoelectric substrate tomaintain structural integrity.

The laser marking can include using a deep ultraviolet laser. The lasermarking can include using a laser with a wavelength of about 266nanometers.

Grinding the back side of the piezoelectric substrate can includegrinding the back side of the piezoelectric substrate until a thicknessof the piezoelectric substrate is about 130 micrometers.

The piezoelectric substrate can include lithium niobate. Thepiezoelectric substrate can include lithium tantalite.

The method can additionally include forming a structure supported by thefront side of the piezoelectric substrate and defining a cavityenclosing the interdigital transducer electrode. The structure supportedby the front side of the piezoelectric substrate can be formed beforegrinding the back side of the piezoelectric substrate. Forming thestructure supported by the front side of the piezoelectric substrate caninclude forming a photosensitive resin buffer coat.

Another aspect of this disclosure is a method of marking a packagedsurface acoustic wave device, the method including forming a packagingstructure on a first surface of a piezoelectric substrate on which aninterdigital transducer electrode of the surface acoustic wave device isdisposed, the packaging structure encapsulating the interdigitaltransducer electrode in a cavity, and directly marking a second surfaceof the piezoelectric substrate to form a marked portion of thepiezoelectric substrate.

Directly marking the second surface of the piezoelectric substrate caninclude exposing the marked portion of the second surface of thepiezoelectric substrate to laser light. The laser light can include deepultraviolet light. The laser light can have a wavelength of about 266nanometers.

Forming a packaging structure can include forming a layer ofphotosensitive resin and patterning the layer of photosensitive resin.The photosensitive resin can include a phenol resin. Forming a packagingstructure can include forming a conductive terminal extending throughthe layer of photosensitive resin.

The marking can extend less than 1 micron into the piezoelectricsubstrate. The packaged surface acoustic wave device can have athickness of less than 220 micrometers.

Another aspect of this disclosure is a packaged surface acoustic wavedevice that includes a cavity roof over interdigital transducers of asurface acoustic wave device, a plate over the cavity roof, and aphotosensitive buffer coat layer over the plate, the packaged surfaceacoustic wave device having a height of 220 micrometers or less.

The packaged surface acoustic wave device can have a height of 200micrometers or less. The photosensitive buffer coat layer can have aheight of 15 micrometers or less.

The packaged surface acoustic wave device can additionally include apiezoelectric substrate having a first side on which the interdigitaltransducers are disposed, an edge portion of the first side of thepiezoelectric substrate can be free from the photosensitive buffer coatlayer.

The packaged surface acoustic wave device can additionally include apiezoelectric substrate having a first side and a second side oppositethe first side, the interdigital transducers can be on the first side,and marking can extend into the second side. The marking can extend 1micrometer or less into the piezoelectric substrate.

The packaged surface acoustic wave device can additionally include aterminal in physical contact with the plate though an opening in thephotosensitive buffer coat layer.

The photosensitive buffer coat layer can include phenol resin. Thephotosensitive buffer coat layer can have a negative photosensitivity.

The packaged surface acoustic wave device can include a surface acousticwave device configured to filter a radio frequency signal.

Another aspect of this disclosure is a packaged surface acoustic wavedevice that includes a piezoelectric substrate having a first side and asecond side opposite the first side, the second side having markingsextending therein, a cavity roof over interdigital transducers of thesurface acoustic wave device on the first side of the piezoelectricsubstrate, a plate over the cavity roof, and an insulating layer overthe plate.

Another aspect of this disclosure is a packaged surface acoustic wavedevice that includes a piezoelectric substrate, a cavity roof overinterdigital transducers of the surface acoustic wave device, theinterdigital transducers being disposed on the piezoelectric substrate,a plate over the cavity roof, and an insulating layer over the plate, anedge portion of the piezoelectric substrate being free from theinsulating layer.

Another aspect of this disclosure is a packaged surface acoustic wavedevice that includes a cavity roof over interdigital transducers of asurface acoustic wave device, a plate over the cavity roof, and aninsulating layer over the plate, the insulating layer having a thicknessof 10 micrometers or less, and the packaged surface acoustic wave devicehaving a height of 200 micrometers or less.

Another aspect of this disclosure is a method of manufacturing apackaged surface acoustic wave device, the method including forming aphotosensitive resin over a plate, the plate being positioned over acavity roof enclosing interdigital transducers of the surface acousticwave device, and forming a terminal of the surface acoustic wave deviceover the photosensitive resin such that the terminal is in contact withthe plate.

The method can additionally include exposing portions of thephotosensitive resin to light and making other portions of thephotosensitive resin to provide an opening though the photosensitiveresin, where forming the terminal can include filling the opening withmaterial of the terminal.

The method can additionally include exposing the photosensitive resin tolight and making other portions of the photosensitive resin to providean edge of a piezoelectric substrate free from the photosensitive resin,and the interdigital transducer electrodes can be positioned on thepiezoelectric substrate.

The photosensitive resin can have a thickness of 15 micrometers or less.The photosensitive resin can include phenol resin.

The method can additionally include laser marking a piezoelectricsubstrate on which the interdigital transducers are disposed.

Another aspect of this disclosure is a method of marking a packagedsurface acoustic wave device, the method including grinding a back sideof a piezoelectric substrate, the back side being opposite a front sideof the piezoelectric substrate on which interdigital transducers of thesurface acoustic wave device are disposed, and laser marking thepiezoelectric substrate.

The marking can extend less than 1 micron into the piezoelectricsubstrate.

The laser marking can include applying a wavelength of laser light thatallows the piezoelectric substrate to maintain structural integrity. Thelaser marking can include using a deep ultraviolet laser.

For purposes of summarizing the disclosure, certain aspects, advantagesand novel features of the innovations have been described herein. It isto be understood that not necessarily all such advantages may beachieved in accordance with any particular embodiment. Thus, theinnovations may be embodied or carried out in a manner that achieves oroptimizes one advantage or group of advantages as taught herein withoutnecessarily achieving other advantages as may be taught or suggestedherein.

The present disclosure relates to U.S. patent application Ser. No.16/555,985, titled “METHODS FOR PACKAGING SURFACE ACOUSTIC WAVEDEVICES,” filed on even date herewith, the entire disclosure of which ishereby incorporated by reference herein. The present disclosure relatesto U.S. patent application Ser. No. 16/555,860, titled “LASER-MARKEDPACKAGED SURFACE ACOUSTIC WAVE DEVICES,” filed on even date herewith,the entire disclosure of which is hereby incorporated by referenceherein. The present disclosure relates to U.S. patent application Ser.No. 16/555,901, titled “METHODS FOR LASER MARKING PACKAGED SURFACEACOUSTIC WAVE DEVICES,” filed on even date herewith, the entiredisclosure of which is hereby incorporated by reference herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of this disclosure will now be described, by way ofnon-limiting example, with reference to the accompanying drawings.

FIG. 1 is a cross sectional diagram of a packaged surface acoustic wavedevice according to an embodiment.

FIG. 2A is another cross section diagram of a packaged surface acousticwave device according to another embodiment. FIG. 2B is a detailed viewof section B of FIG. 2A.

FIGS. 3A-3J are cross-sections of a portion of a packaged surfaceacoustic wave device at various stages of a manufacturing processaccording to an embodiment.

FIGS. 4A-4F are cross-sections of a portion of a partially packagedsurface acoustic wave device at various stages of a manufacturingprocess including multiple photoresist exposures according to anotherembodiment.

FIGS. 5A-5E are cross-sections of a portion of a partially packagedsurface acoustic wave device at various stages of a manufacturingprocess including a plating process according to another embodiment.

FIGS. 6A-6C are cross-sections of a portion of a partially packagedsurface acoustic wave device at various stages of a manufacturingprocess including a spin-coating process according to anotherembodiment.

FIG. 7 is a flow diagram of a process of manufacturing a packagedsurface acoustic wave device including a photosensitive buffer coataccording to an embodiment.

FIG. 8 is a flow diagram of a process of manufacturing a packagedsurface acoustic wave device including laser marking of a piezoelectriclayer according to an embodiment.

FIG. 9 is a schematic diagram of a radio frequency module that includesa filter with SAW resonators according to an embodiment.

FIG. 10 is a schematic diagram of a radio frequency module that includesduplexers with surface acoustic wave resonators according to anembodiment.

FIG. 11 is a schematic block diagram of a module that includes a poweramplifier, a radio frequency switch, and duplexers that include one ormore surface acoustic wave resonators according to an embodiment.

FIG. 12 is a schematic block diagram of a module that includes a lownoise amplifier, a radio frequency switch, and surface acoustic wavefilters according to an embodiment.

FIG. 13 is a schematic block diagram of a module that includes anantenna switch and duplexers that include one or more surface acousticwave resonators according to an embodiment.

FIG. 14 is a schematic block diagram of a wireless communication devicethat includes a surface acoustic wave filter in accordance with one ormore embodiments.

FIG. 15 is a schematic block diagram of another wireless communicationdevice that includes a surface acoustic wave filter in accordance withone or more embodiments.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

The following description of certain embodiments presents variousdescriptions of specific embodiments. However, the innovations describedherein can be embodied in a multitude of different ways, for example, asdefined and covered by the claims. In this description, reference ismade to the drawings where like reference numerals can indicateidentical or functionally similar elements. It will be understood thatelements illustrated in the figures are not necessarily drawn to scale.Moreover, it will be understood that certain embodiments can includemore elements than illustrated in a drawing and/or a subset of theelements illustrated in a drawing. Further, some embodiments canincorporate any suitable combination of features from two or moredrawings.

As the semiconductor market becomes increasingly competitive, there aremore demands for smaller and thinner packaged surface acoustic wavedevices. For instance, in certain applications, specifications call forsurface acoustic wave device package heights of 200 microns or less sothat the packaged surface acoustic wave devices can fit into a module.Methods of packaging are disclosed can achieve lower profile and lowercost for a package of a surface acoustic wave device. Surface acousticwave devices with Wafer Level Chip Scale Packaging (WL-CSP) for surfaceacoustic wave filters with thinner packages are disclosed.

Methods of packaging surface acoustic wave devices are disclosed toreduce package height and/or lower packaging costs. Package structuresdisclosed herein include a photosensitive buffer coat layer, which actsas a protective layer covering a copper (Cu) plating. With a thinphotosensitive buffer coat layer, the package structure can be formedwithout a post structure connecting a terminal to internal conductivestructures of the package. Package structures disclosed herein includemarking on a piezoelectric substrate of a surface acoustic wave device.A laser can mark the piezoelectric substrate without damaging thefunctionality of the piezoelectric substrate. Package structuresdisclosed herein can meet electrical performance and moldabilitystrength specifications. The packaged surface acoustic wave devicesdisclosed herein can include surface acoustic wave filters arranged tofilter radio frequency signals.

FIG. 1 is a cross sectional diagram of a packaged surface acoustic wavedevice according to an embodiment. Certain aspects of the packagedsurface acoustic wave device 100 allow the thickness of the package tobe reduced. For example, the packaged surface acoustic wave device 100can have a package height H₁ of less than 220 micrometers (μm). Incertain embodiments, the package height H₁ can be less than 200 um. Inone exemplary embodiment, the packaged surface acoustic wave device 100has a package height H₁ of approximately 190 um.

As illustrated in FIG. 1 , the packaged surface acoustic wave device 100includes a die 102, and interdigital transducer electrodes 104 on thedie 102. The die 102 is a piezoelectric substrate. The die 102 caninclude a lithium-containing piezoelectric material, such as a lithiumniobate or lithium tantalate, for example. In some instances, the die102 includes a multi-layer piezoelectric substrate. The die 102 can beapproximately 130 um tall in certain instances. Other suitablethicknesses may also be used in other embodiments.

The die 102 can include a marked section 108 on a side of the die 102opposite the interdigital transducer electrodes 104. The marked section108 can be relatively shallow, compared to the overall thickness of thedie 102. In some embodiments, the markings of the marked section 108 canextend less than 1 um into the die. By marking directly into the die102, no additional marking film is included in the packaged surfaceacoustic wave device 100 of FIG. 1 . This can reduce the overall heightof the packaged surface acoustic wave device 100 relative to packagedsurface acoustic wave devices that include marking films.

Interdigital transducer electrodes 104 of surface acoustic waveresonators are disposed on the die 102. The surface acoustic waveresonators can be arranged as a filter configured to filter a radiofrequency signal. Any suitable number of surface acoustic waveresonators and/or surface acoustic wave filters can be included in thepackaged surface acoustic wave device 100.

The interdigital transducer electrodes 104 are disposed within a cavity116. The sides of the cavity 116 are formed by cavity walls 112supported by the die 102. The roof of the cavity 116 is formed by acavity roof 114 supported by the cavity walls 112 and extending over theinterdigital transducer electrodes 104. The cavity 116 may be an aircavity. In some embodiments, the cavity 116 may be about 25 um tall,although other suitable cavity heights may also be used.

In some embodiments, one or both of the cavity roof 114 and the cavitywalls 112 may include a photoresist material, as discussed in greaterdetail below.

Portions of the outer surfaces of the cavity roof 114 and the cavitywalls 112 are covered by a conductive layer 122. In some embodiments,the conductive layer 122 may be formed by covering the outer surfaces ofthe cavity roof 114 and the cavity walls 112 with a seed layer, and thenforming the conductive layer 122 over the seed layer using a platingprocess. The conductive layer 122 may include more than one section,which may be electrically isolated from one another by at least one gap124 in the conductive layer 122. The conductive layer 122 may be about25 um in thickness in certain embodiments, although other suitablethicknesses may also be used.

In some embodiments, the conductive layer 122 includes a layer of copperwhich is plated onto a seed layer including copper and/or titanium.

The conductive layer 122 may extend along the sides of the cavity walls112, and down to the die 102, where the conductive layer 122 may contactinterconnect structures such as electronic traces on the die 102,allowing electrical communication with the interdigital transducerelectrodes 104 of surface acoustic wave resonator structures within thepackaged surface acoustic wave device 100. The conductive layer 122 canbe referred to as a plate layer in certain applications.

An insulation layer 132 extends over outer surfaces of the conductivelayer 122, and fills the gap 124 in the conductive layer 122. Sideportions 136 of the insulation layer 132 extend down the sides of theconductive layer 122 to the die 102. In certain embodiments, theinsulation layer 132 is a photosensitive resin. In some embodiments, theconductive layer 122 may be a negative photoresist. In some embodiments,the photosensitive resin can be a phenol resin with rubber filler. Sucha resin may have a viscosity of about 700 centipoise (cP), and may havea shelf life of about 9 months at 5° C., and a floor life of about 4months. The cured resin may have a Young's modulus of elasticity ofabout 2.2 gigapascals (GPa), and a coefficient of thermal expansion ofroughly 55/° C.

The insulation layer 132 can be made relatively thin. In someembodiments, the insulation layer may be about 15 um thick or less. Insome embodiments, the thickness of an insulation layer 132 includingphenol resin with rubber filler can be in a range from about 6 um toabout 14 um. In some particular embodiments, the thickness of aninsulation layer 132 including phenol resin with rubber filler may beabout 10 um. The formation of the insulation layer 132 using a materialsuch as the photosensitive resin can reduce the overall height of thepackaged surface acoustic wave device 100 relative to other devices withthicker insulation layers.

In addition to the reduction in thickness, a photosensitive buffer coatlayer as an insulation layer 132 can be removed to provide nosignificant residue on other portions of the die 102, such as theopening and saw street area where die are diced and singulated. The useof photosensitive buffer coat layer can also provide good coverage onthe surfaces of a copper conductive layer, without significant copperoxidation after buffer coat curing. A photosensitive buffer coat layercan also pass ball shear and reliability tests.

The insulation layer 132 can be a photosensitive buffer coat layer. Insome embodiments, negative-type photosensitive material can be used asthe photosensitive buffer coat layer. The photosensitive buffer coatlayer can be thicker at the saw street at the edge of the device, due tothe trench made by the height of the cavity wall, cavity roof, andconductive layer. For positive-type photosensitive material, where thearea of the photosensitive material to be removed is exposed to light,and exposure energy can be a significant factor in removing residue. Arelatively high exposure dose can be applied in order to developpositive-type photosensitive material, to penetrate the relatively thickbuffer coat at the edge of the device. This can make it difficult todevelop positive material when exposure energy is not sufficiently high.With relatively high exposure energy, there can be thinning of the edgesclose to the saw street.

In contrast, for negative-type photosensitive material, the area of thephotosensitive buffer intended to remain in the finished device isexposed to light. The development rate can depend on the properties ofthe photosensitive material. A negative-type photosensitive material canbe easily developed at the saw street area at the side of the packagedsurface acoustic wave device.

The packaged surface acoustic wave device 100 also includes terminals142 a and 142 b located above respective portions of the conductivelayer 122 and in physical contact with the conductive layer 122 throughapertures in the insulation layer 132. Portions 144 a and 144 b ofterminals 142 a and 142 b, respectively, extend through the apertures inthe insulation layer 132. Solder layers 146 a and 146 b overlie theterminals 142 a and 142 b, respectively.

A conformal layer overlying the patterned insulation layer 132 can formboth the connective portions 144 a and 144 b and the remainder of theterminals 142 a and 142 b. In such an embodiment, the terminal and theunderlying conductive layer can be formed without a separate postbetween the two, connecting them. The terminal can include copper, oranother suitable material. In some embodiments, the terminal may have athickness of about 10 um. The solder layers 146 a and 146 b may includetin.

FIG. 2A is a diagram of a packaged surface acoustic wave device 200according to an embodiment. FIG. 2B is a detail view of section B ofFIG. 2A, illustrating the edge portion of the packaged surface acousticwave device 200. As can be seen in FIG. 2B, the cavity walls 212 have athickness T_(W), the sidewall 226 of the conductive material 222 alongthe edge of the device has a thickness of T_(C), and the distance fromthe outer edge of the sidewall 236 of the conductive material 232 to theedge of the die 202 has a thickness of T_(E). In some embodiments, thethickness T_(W) of the cavity walls 212 is about 30 um, the thicknessT_(C) of the portion of the sidewall 226 of the conductive material 222in contact with die 202 is about 15 um, and the thickness T_(E) from theouter edge of the sidewall 236 of the conductive material 232 to theedge of the die 202 is about 30 um.

FIG. 2B illustrates that an edge portion 206 of the wafer substrate isfree from the photosensitive resin forming the insulation layer 232,such that the side 236 of the insulation layer 232 is set back from theouter edge of the die 202. The edge portion can extend a distance in arange from about 10 um to 20 um from an edge of the insulation layer 232to an edge of the die 202. This allows the saw street area, where dieare diced and singulated, to be free from the encapsulation of theinsulating layer. This in turn allows the use of a relatively thinnerblade to singulate die. This can facilitate smaller spacing betweenadjacent die and more die on a wafer of a given size. Moreover, athinner blade for singulation can improve reliability by reducingchipping.

FIGS. 3A-3J are cross-sections of a portion of a packaged surfaceacoustic wave device at various stages of a manufacturing processaccording to an embodiment. In the stage shown in FIG. 3A, a die 302 isprovided, including interdigital transducer electrodes 304 of one ormore surface acoustic wave resonators. The die 302 may in someembodiments be a wafer with a plurality of discrete regions containinginterdigital transducer electrodes which will be packaged into separatepackaged surface acoustic wave devices and then separated in asingulation process. The die 302 may be a single piezoelectric layer, asshown. In other embodiments, the die 302 may be a multilayerpiezoelectric substrate, including a support substrate in addition to apiezoelectric substrate. A multilayer piezoelectric substrate caninclude one or more additional layers along with the support substrateand the piezoelectric substrate. As one example, the support substratecan be a silicon substrate. In addition to the interdigital transducerelectrodes 304, interconnect structures extending away from theinterdigital transducer electrodes 304 may also be provided on the die302.

In FIG. 3B, a cavity wall 312 has been formed, circumscribing theinterdigital transducer electrodes 304. The cavity wall 312 may be asingle wall with curved sections, or may include a plurality of wallsegments meeting one another at angles to form a desired shape, such asa rectangle. The cavity wall 312 may include a photoresist or otherphotosensitive material. The height of the cavity wall 312 maycorrespond to a desired height of the resulting cavity. The cavity wall312 may extend over interconnect structures supported by the die 302, sothat a portion of the interconnect structure is located outside of thecavity wall 312. Cavity walls 312 may be formed at multiple locationsacross a wafer including piezoelectric material, each at a location of apackage being formed.

In FIG. 3C, a cavity roof 314 has been formed, extending from one sideof the cavity wall 312 to the other side. In the illustrated embodiment,the cavity roof 314 is a planar structure with an upper surface and alower surface extending generally parallel to one another and to theunderlying surface of the die 302. In some other embodiments, othershapes of cavity roofs may be formed, including shapes with a recess inthe lower surface of the cavity roof facing the interdigital transducerelectrodes 304. In the illustrated embodiment, the edges of the cavityroof 314 do not extend outward beyond the edges of the cavity wall 312.This shape may facilitate deposition of subsequent materials over thecavity-defining structure.

In FIG. 3D, a seed layer has been deposited over the outer surfaces ofthe cavity roof 314 and the cavity wall 320, and a conductive layer 322has been formed at certain locations overlying the seed layer. Theconductive layer 322 includes a gap 324 between two portions of theconductive layer 322. The conductive layer 322 also includes a sidewallportion 326 extending along the side of the cavity roof 314 and thecavity wall 312 and extending down to the die 302.

In FIG. 3E, exposed portions of the seed layer have been removed, and abuffer coat insulating layer 332 has been formed over the conductivelayer 322. The insulating layer 332 has apertures 334 exposingunderlying sections of the conductive layer 322. The insulation layer332 also includes a sidewall portion 336 extending along the sides ofthe conductive layer 322 and down to the die 302. The insulating layer332 may include a negative-type photosensitive material. The insulatinglayer 332 may include a photosensitive resin. The insulating layer 332may include a phenol resin with rubber filler.

In FIG. 3F, terminals 340 a and 340 b have been formed overlying theapertures 334 in the insulation layer 332. The terminals 340 a and 340 bfill at least part of the apertures 334 and extend over the portions ofthe insulation layer 332 adjacent the apertures 334. In someembodiments, the terminals 340 a and 340 b may include copper or anothersuitable conductive material. The terminals 340 a and 340 b may includea layer of conformal material deposited over the apertures 334 and overthe portions of the insulation layer 332 adjacent the apertures 334,such that the terminals 340 a and 340 b include respective connectingportions 344 a and 344 b within the apertures 334 and wider uppersections 342 a and 342 b above the connecting portions 344 a and 344 b.

In FIG. 3G, solder portions 346 a and 346 b have been formed over theupper surfaces of terminals 340 a and 340 b, respectively. The soldermay include tin, in some embodiments, although other suitable soldermaterial may be used as well. The solder portions 346 a and 346 b mayfacilitate bonding of the terminals 340 a and 340 b to external devices,making connections through the conductive material 322 with the surfaceacoustic wave resonators within the cavity 316.

In FIG. 3H, the side of the die 302 opposite the interdigital transducerelectrodes 304 is back ground to remove a portion 309 of the die 302 inorder to reduce the thickness of the die 302 to a desired finalthickness. In some embodiments, the resulting trimmed die 302′ may havean ultimate thickness of about 130 um, although other die thicknessesmay also be used.

In FIG. 3I, the side 307 of the trimmed die 302′ opposite theinterdigital transducer electrodes 304 is exposed to illumination 390from a marking laser to form marked and trimmed die 302″ having a markedportion 308. Laser marking can be used for alignment of a module and/orfor identifying a wafer and lot of a module. Laser marking can beperformed directly on the piezoelectric material of trimmed die 302′ asillustrated. By marking the trimmed die 302′ directly, rather thanforming an additional film or layer to be marked, the overall thicknessof the resultant packaged surface acoustic wave device 300 can bereduced.

This direct marking can use illumination 390 from a deep ultravioletlaser. In one embodiment, such a laser can emit light having awavelength that can mark a lithium-based substrate without damagingfunctionality of the lithium-based substrate for the surface acousticwave device. As an example, the laser light can have a wavelength of 266nanometers (nm). This wavelength of laser light, or a similarwavelength, can mark a lithium-based substrate, such as a lithiumniobite substrate or a lithium tantalite substrate, to a relativelyshallow depth, such as a depth of less than 1 micron. This shallowmarking depth can prevent can a significant reduction of the strength oftrimmed and marked die 302″. In addition, this wavelength of laser lightshould not penetrate through the lithium niobate substrate. A multilayerpiezoelectric substrate can be similarly marked using suitable laserwavelengths.

FIG. 3J shows the marked packaged surface acoustic wave device 300,including a detail view of the marked portion 308 of the side 307 of thetrimmed die 302′ opposite the interdigital transducer electrodes 304.The detail view illustrates the markings 392 in the marked portion 308of the underside 307 of the die 302″. Any suitable markings, includingalphanumeric markings or other symbols, may be formed. The location ofthe marked portion 308 may be at any suitable location or locations onthe die 302″.

The resultant packaged surface acoustic wave device 300 can have anoverall package height H₁ of less than 220 um, and in certainembodiments may be less than 200 um or approximately 190 um. Featureswhich reduce the overall package height H₁ of device 300 include the useof a buffer coat layer to form insulation layer 332, and the directmarking of die 302″ rather than the formation and marking of a separatelayer. In addition, the process illustrated in FIGS. 3A-3J, a surfaceacoustic wave device can be packaged with fewer processing steps (e.g.,about 25 fewer) than certain previous methods.

Although FIGS. 3B and 3C broadly illustrate the formation of cavity wall312 and cavity roof 314, FIGS. 4A-4F illustrate in greater detail aspecific embodiment of a manufacturing process for forming a cavity walland a cavity roof. In particular, FIGS. 4A-4F show cross-sections of aportion of a partially packaged surface acoustic wave device at variousstages of a manufacturing process including multiple photoresistexposures.

FIG. 4A shows the formation of a photosensitive layer 450 over a die 402and interdigital transducer electrodes 404 supported by the die 402. Thedie 402 and interdigital transducer electrodes 404 may be similar to thedie 302 and interdigital transducer electrodes 304 of FIG. 3A. Thephotosensitive layer 450 may include a photosensitive material, and maybe formed having a thickness equal to the desired thickness of a cavitywall. Because the interdigital transducer electrodes 404 and othercomponents supported by die 402 may provide an irregular upper surfaceon which the photosensitive layer 450 is formed, the photosensitivelayer 450 may be formed by using a liquid type of photosensitivematerial, such as a liquid photoresin. The use of a liquidphotosensitive material allows the formation of a photosensitive layer450 of substantially constant thickness across the die 402 and over theinterdigital transducer electrodes 404.

FIG. 4B shows the selective exposure of portions of the photosensitivelayer 450 to illumination 490 using a mask 452. In the illustratedembodiment, the photosensitive layer 450 includes a positive-typephotosensitive material, where the portions of the photosensitive layer450 to remain in the device are shielded from light, and the portions454 of the photosensitive layer 450 to be removed are exposed to light.The masked portions of photosensitive layer 450 can remain insoluble toa photoresist developer and the unmasked portions 454 of thephotosensitive layer 450 that are exposed to light can become soluble toa photoresist developer.

FIG. 4C shows the masked portions of the photosensitive layer 450 ofFIG. 4B remaining as cavity walls 412 after removal of the unmaskedportions of the photosensitive layer. This removal may include, forexample, exposure of the photosensitive layer 450 to a photoresistdeveloper to remove the soluble portions of the photosensitive layer.

In FIG. 4D, a photoresist layer 460 has been formed over the cavitywalls 412. In contrast to the photoresist material 450 which may includea liquid type photoresin to provide a constant thickness over anirregular surface, the photoresist layer 460 may be deposited as a filmsupported by the cavity walls, so that a generally planar structure maybe formed overlying the interdigital transducer electrodes 404 and othercomponents supported by die 402.

In FIG. 4E, the photosensitive layer 460 is selectively exposed toillumination 490 using a mask 462. In the illustrated embodiment, thephotosensitive layer 460 includes a negative-type photosensitivematerial, where the portions of the photosensitive layer 460 to remainin the device are exposed light, and the portions 464 of thephotosensitive layer 460 to be removed are shielded from light. Themasked portions of photosensitive layer 450 can remain soluble to aphotoresist developer and the unmasked portions 454 of thephotosensitive layer 450 that are exposed to light can remain insolubleto a photoresist developer.

FIG. 4F shows the unmasked portion of the photosensitive layer 460 ofFIG. 4E remaining as a cavity roof 414 after removal of the maskedportions of the photosensitive layer. This removal may include, forexample, exposure of the photosensitive layer 460 to a photoresistdeveloper to remove the soluble portions of the photosensitive layer.

Although FIG. 3D broadly illustrates the formation of conductive layer322, FIGS. 5A-5F illustrate in greater detail a specific embodiment of amanufacturing process for forming a conductive layer using a platingprocess. In particular, FIGS. 5A-5E are cross-sections of a portion of apartially packaged surface acoustic wave device at various stages of amanufacturing process including a plating process.

FIG. 5A shows that a seed layer 520 has been formed over the outsidesurfaces of a cavity wall 512 and a cavity roof 514. Like the partiallypackaged device of FIG. 4F, the cavity wall 512 and a cavity roof 514are supported by a die 502 and define a cavity 516 enclosinginterdigital transducer electrodes 504 supported by the die 502. Theformation of the seed layer 520 may include performing surfacemodification on exposed surfaces of the cavity roof 514 or othersurfaces, including cleaning these surfaces. Metal can then be sputteredover the cavity roof 514 and the exposed surfaces of the cavity wall 512to form the seed layer 520. In some embodiments, titanium and copper canbe sputtered to form a base metal for plating. The seed layer 520 mayextend onto exposed portions of the die 502 adjacent the cavity walls512.

In FIG. 5B, a photosensitive layer 570 has been formed over the seedlayer 520. The photosensitive layer 570 may be generally conformal overthe underlying structure as shown, but in other embodiments may bethinner over the cavity roof 514 than over the die on the side. Thephotosensitive layer 570 may have a thickness in the area overlying thecavity roof 514 at least as thick as the eventual conductive layer to beplated onto the seed layer, so that the photosensitive layer 570 can beused to define the shape of the conductive layer to be plated onto theseed layer 520.

In FIG. 5C, the photosensitive layer 570 has been patterned, viaselective exposure of the photosensitive layer 570 to illumination andsubsequent removal of soluble portions of the photosensitive layer 570.This removal of portions of the photosensitive layer exposes portions ofthe underlying seed layer 520.

The remaining photosensitive layer portions include side portions 574defining the edges of the conductive layer to be formed. These sideportions 574 may overlie only portions of the seed layer 520 on theunderlying die 502 away from the cavity walls 512. The remainingphotosensitive layer portions also include a gap-defining portion 572extending over a portion of the cavity roof 514. The gap-definingportion 572 may in some embodiments extend from one side portion 574 toanother side portion 574, completely separating two exposed sections ofthe seed layer 520 from one another. In some embodiments, additionalgap-defining portions may be included to separate the exposed portionsof the seed layer 530 into multiple separate sections.

In FIG. 5D, a thicker conductive layer 522 has been plated onto theexposed portions of the seed layer 520. The shape of the thickerconductive layer 522 is defined by the remaining portions of thephotosensitive layer, including the side portions 574 and thegap-defining portion 572. The conductive layer 522 may include copper orany other suitable material.

In FIG. 5E, the remaining portions of the photosensitive layer,including the side portions 574 and the gap-defining portion 572, havebeen removed. In addition, the exposed portions of the seed layer 520underlying these portions of the photosensitive layer have been removed.The resulting conductive layer 522 may include discrete sectionsoverlying the cavity roof 514, separated by a gap 524, as well assidewall sections 526 extending along the sides of the cavity roof 514and the cavity wall 512, down to the die 502.

Although FIG. 3E broadly illustrates the formation of insulating layer332, FIGS. 6A-6C illustrate in greater detail a specific embodiment of amanufacturing process for forming an insulating layer. In particular,FIGS. 6A-6C show cross-sections of a portion of a partially packagedsurface acoustic wave device at various stages of a manufacturingprocess including a spin-coating process.

FIG. 6A shows that a buffer coat layer 680 has been formed over theoutside surfaces of a conductive layer 622 formed over a cavity wall 612and a cavity roof 614. Like the partially packaged device of FIG. 5E,the cavity wall 612 and a cavity roof 614 are supported by a die 602 anddefine a cavity 616 enclosing interdigital transducer electrodes 604supported by the die 602. In some embodiments, the buffer coat layer mayinclude a photosensitive resin such as phenol resin. The buffer coatlayer may also include a rubber filler.

In the illustrated embodiment, the thickness of the buffer coat layer680 overlying the conductive layer 622 is thinner than the thickness ofthe buffer coat layer 680 overlying the die 602 away from the conductivelayer 622. The upper surface of the buffer coat layer 680 may begenerally planar. In some embodiments, the buffer coat layer 680 may bedeposited using a spin-coating process. The use of a spin-coatingprocess may provide the generally planar upper surface despite theirregular profile of the underlying conductive layer 622 and die 602.The thickness of the buffer coat layer 680 in the area overlying thecavity roof 614 may in some embodiments be less than about 10 um,although other suitable thicknesses may also be used.

In FIG. 6B, the buffer coat layer 680 is selectively exposed toillumination 690 using a mask 682. In the illustrated embodiment, thebuffer coat layer 680 includes a negative-type photosensitive material,where the portions of the buffer coat layer 680 to remain in the deviceare exposed to light, and the portions 684 of the buffer coat layer 680to be removed are shielded from light. The masked portions 684 of buffercoat layer 680 can remain soluble to a photoresist developer and theunmasked portions of the buffer coat layer 680 that are exposed to lightcan become insoluble to a photoresist developer. Broad band light may beused to expose the buffer coat layer 680.

In FIG. 6C, the masked portions of the buffer coat layer 680 have beenremoved, and the remaining portions have been cured to form aninsulation layer 632 extending over the conductive layer 622. Theinsulating layer 632 has apertures 634 exposing underlying sections ofthe conductive layer 622. The insulation layer 632 also includes asidewall portion 636 extending along the sides of the conductive layer622 and down to the die 602.

FIG. 7 is a flow diagram of a process of manufacturing a packagedsurface acoustic wave device including a photosensitive buffer coataccording to an embodiment. The process 700 begins at a stage 705 wherea cavity structure is formed on a die supporting at least oneinterdigital transducer electrode. The cavity structure encapsulates theat least one interdigital transducer electrode. The formation of thecavity structure can include the formation of a cavity wall or wallssurrounding the at least one interdigital transducer electrode and theformation of a cavity roof supported by the cavity walls and extendingover the at least one interdigital transducer electrode.

The process 700 moves to a stage 710 where a conductive layer is formedover the cavity structure including the cavity roof and cavity wall. Theconductive layer may be formed by a plating process. The plating processmay include the deposition, such as via sputtering, of a seed layer,followed by plating of the conductive layer onto the seed layer. Theconductive layer may include sidewall portions in contact with the die.The conductive layer may include sections which are electricallyseparated from one another.

The process 700 moves to a stage 715 where an insulation layer is formedover the conductive layer using a spin-coating process. The insulationlayer may include a buffer coat layer. The buffer coat layer may includea phenol resin, and may include rubber filler. The insulation layer mayinclude a negative photoresist material. The insulation layer mayinclude a plurality of apertures exposing different portions of theconductive layer. The insulation layer may include sidewall portions incontact with the die.

The process 700 moves to a stage 720, where a plurality of terminals areformed, each overlying and extending into an aperture in the insulationlayer to contact the conductive layer. The terminals may include copper.The terminals may include a solder layer on top of the terminal.

FIG. 8 is a flow diagram of a process of manufacturing a packagedsurface acoustic wave device including laser marking of a piezoelectriclayer according to an embodiment. The process 800 can be performed incombination with the process 700 in certain applications. The process800 begins at a stage 805 where a piezoelectric substrate supporting apackaged surface acoustic wave device is provided. The packaged surfaceacoustic wave device may include at least one interdigital transducerelectrode encapsulated within a cavity structure. The packaged surfaceacoustic wave device may include an insulation layer formed by a spin-onprocess. The insulation layer may include a negative photoresist, whichmay be a phenol resin, and may include rubber filler. The packagedsurface acoustic wave device

The process 800 moves to a stage 810 where the piezoelectric substrateis directly laser marked. The marking process does not increase thethickness of the packaged surface acoustic wave device, as no discretemarking layer is included. The laser marking may include using a deep UVlaser to mark the piezoelectric substrate. The laser making can involveapplying laser light having a wavelength of 266 nm in certain instances.Such a wavelength is suitable for marking lithium niobate and/or lithiumtantalate substrates. The marked portion of the piezoelectric substratemay extend less than 1 um into the piezoelectric substrate.

The packaged surface acoustic wave devices disclosed herein can beimplemented in a variety of applications, such as standalone surfaceacoustic wave filters, in radio frequency modules, or the like. Radiofrequency modules that include packaged surface acoustic wave device inaccordance with any suitable principles and advantages disclosed hereincan also include one or more of a power amplifier, a radio frequencyswitch, a low noise amplifier, an inductor, or the like. Such radiofrequency modules can benefit from reduced height and/or size of thepackaged surface acoustic wave device.

FIG. 9 is a schematic diagram of a radio frequency module 900 thatincludes a surface acoustic wave component 1076 according to anembodiment. The illustrated radio frequency module 1200 includes the SAWcomponent 1076 and other circuitry 1077. The SAW component 1076 caninclude one or more packaged SAW filters with any suitable combinationof features of the SAW packages disclosed herein.

The SAW component 1076 shown in FIG. 9 includes a filter 1078 andterminals 1079A and 1079B. The filter 1078 includes SAW resonators, andmay be packaged in accordance with any suitable principles andadvantages disclosed herein. The terminals 1079A and 1079B can serve,for example, as an input contact and an output contact, and may extendthrough a buffer coat resin insulation layer. The SAW component 1076 andthe other circuitry 1077 are on or supported by a common packagingsubstrate 1080 in FIG. 9 . The package substrate 1080 can be a laminatesubstrate. The terminals 1079A and 1079B can be electrically connectedto contacts 1081A and 1081B, respectively, on or supported by thepackaging substrate 1080 by way of electrical connectors 1082A and1082B, respectively. The electrical connectors 1082A and 1082B can bebumps or wire bonds, for example. The other circuitry 1077 can includeany suitable additional circuitry. For example, the other circuitry caninclude one or more one or more power amplifiers, one or more radiofrequency switches, one or more additional filters, one or more lownoise amplifiers, the like, or any suitable combination thereof. Theradio frequency module 1200 can include one or more packaging structuresto, for example, provide protection and/or facilitate easier handling ofthe radio frequency module 1200. Such a packaging structure can includean overmold structure formed over the packaging substrate 1200. Theovermold structure can encapsulate some or all of the components of theradio frequency module 1000.

FIG. 10 is a schematic diagram of a radio frequency module 1000 thatincludes a packaged surface acoustic wave component according to anembodiment. As illustrated, the radio frequency module 1300 includesduplexers 1185A to 1185N that include respective transmit filters 1186A1to 1186N1 and respective receive filters 1186A2 to 1186N2, a poweramplifier 1187, a select switch 1188, and an antenna switch 1189. Theradio frequency module 1300 can include a package that encloses theillustrated elements. The illustrated elements can be disposed on acommon packaging substrate 1180. The packaging substrate can be alaminate substrate, for example.

The duplexers 1185A to 1185N can each include two acoustic wave filterscoupled to a common node. The two acoustic wave filters can be atransmit filter and a receive filter, and may be packaged with oneanother as discussed herein. As illustrated, the transmit filter and thereceive filter can each be band pass filters arranged to filter a radiofrequency signal. A packaged SAW device in accordance with any suitableprinciples and advantages disclosed herein can include one or more SAWresonators of one or more of the transmit filters 1186A1 to 1186N1and/or one or more of the receive filters 1186A2 to 1186N2. AlthoughFIG. 10 illustrates duplexers, any suitable principles and advantagesdisclosed herein can be implemented in other multiplexers (e.g.,quadplexers, hexaplexers, octoplexers, etc.) and/or in switch-plexers.

The power amplifier 1187 can amplify a radio frequency signal. Theillustrated switch 1188 is a multi-throw radio frequency switch. Theswitch 1188 can electrically couple an output of the power amplifier1187 to a selected transmit filter of the transmit filters 1186A1 to1186N1. In some instances, the switch 1188 can electrically connect theoutput of the power amplifier 1187 to more than one of the transmitfilters 1186A1 to 1186N1. The antenna switch 1189 can selectively couplea signal from one or more of the duplexers 1185A to 1185N to an antennaport ANT. The duplexers 1185A to 1185N can be associated with differentfrequency bands and/or different modes of operation (e.g., differentpower modes, different signaling modes, etc.).

FIG. 11 is a schematic block diagram of a module 1210 that includes apower amplifier 1212, a radio frequency switch 1214, and duplexers 1291Ato 1291N in accordance with one or more embodiments. The power amplifier1212 can amplify a radio frequency signal. The radio frequency switch1214 can be a multi-throw radio frequency switch. The radio frequencyswitch 1214 can electrically couple an output of the power amplifier1212 to a selected transmit filter of the duplexers 1291A to 1291N. Apackaged SAW device in accordance with any suitable principles andadvantages disclosed herein can include one or more SAW resonators ofone or more filters of the duplexers 1291A to 1291N and/or one or moreof duplexers 1291A to 1291N.

FIG. 12 is a schematic block diagram of a module 1270 that includesfilters 1271A to 1271N, a radio frequency switch 1274, and a low noiseamplifier 1272 according to an embodiment. A packaged SAW device inaccordance with any suitable principles and advantages disclosed hereincan include one or more SAW resonators of one or more filters of thefilters 1271A to 1271N. Some or all of the filters may be packaged asdiscussed herein. Any suitable number of filters 1271A to 1271N can beimplemented. The illustrated filters 1271A to 1271N are receive filters.In some embodiments (not illustrated), one or more of the filters 1271Ato 1271N can be included in a multiplexer that also includes a transmitfilter. The radio frequency switch 1274 can be a multi-throw radiofrequency switch. The radio frequency switch 1274 can electricallycouple an output of a selected filter of filters 1271A to 1271N to thelow noise amplifier 1272. In some embodiments (not illustrated), aplurality of low noise amplifiers can be implemented. The module 1270can include diversity receive features in certain applications.

FIG. 13 is a schematic block diagram of a module 1395 that includesduplexers 1391A to 1391N and an antenna switch 1394. One or more filtersof the duplexers 1391A to 1391N can be packaged as described herein andmay include any suitable number of surface acoustic wave resonators, inaccordance with any suitable principles and advantages discussed herein.Any suitable number of duplexers 1391A to 1391N can be implemented. Theantenna switch 1394 can have a number of throws corresponding to thenumber of duplexers 1391A to 1391N. The antenna switch 1394 canelectrically couple a selected duplexer to an antenna port of the module1395.

FIG. 14 is a schematic diagram of a wireless communication device 1400that includes filters 1403 in a radio frequency front end 1402 accordingto an embodiment. The filters 1403 can include one or more SAWresonators in accordance with any suitable principles and advantagesdiscussed herein. The wireless communication device 1400 can be anysuitable wireless communication device. For instance, a wirelesscommunication device 1400 can be a mobile phone, such as a smart phone.As illustrated, the wireless communication device 1400 includes anantenna 1401, an RF front end 1402, a transceiver 1404, a processor1405, a memory 1406, and a user interface 1407. The antenna 1401 cantransmit RF signals provided by the RF front end 1402. Such RF signalscan include carrier aggregation signals. Although not illustrated, thewireless communication device 1400 can include a microphone and aspeaker in certain applications.

The RF front end 1402 can include one or more power amplifiers, one ormore low noise amplifiers, one or more RF switches, one or more receivefilters, one or more transmit filters, one or more duplex filters, oneor more multiplexers, one or more frequency multiplexing circuits, thelike, or any suitable combination thereof. The RF front end 1402 cantransmit and receive RF signals associated with any suitablecommunication standards. The filters 1403 may be packaged with oneanother, or with a subset of the filters 1403, and can include packagedSAW devices including any suitable combination of features discussedwith reference to any embodiments discussed herein.

The transceiver 1404 can provide RF signals to the RF front end 1402 foramplification and/or other processing. The transceiver 1404 can alsoprocess an RF signal provided by a low noise amplifier of the RF frontend 1402. The transceiver 1404 is in communication with the processor1405. The processor 1405 can be a baseband processor. The processor 1405can provide any suitable base band processing functions for the wirelesscommunication device 1400. The memory 1406 can be accessed by theprocessor 1405. The memory 1406 can store any suitable data for thewireless communication device 1400. The user interface 1407 can be anysuitable user interface, such as a display with touch screencapabilities.

FIG. 15 is a schematic diagram of a wireless communication device 1510that includes filters 1503 in a radio frequency front end 1502 andsecond filters 1513 in a diversity receive module 1512. The wirelesscommunication device 1510 is like the wireless communication device 1500of FIG. 14 , except that the wireless communication device 1520 alsoincludes diversity receive features. As illustrated in FIG. 15 , thewireless communication device 1520 includes a diversity antenna 1511, adiversity module 1512 configured to process signals received by thediversity antenna 1511 and including filters 1513, and a transceiver1504 in communication with both the radio frequency front end 1502 andthe diversity receive module 1512. The filters 1513 may be packaged withone another, or with a subset of the filters 1513, and can includepackaged SAW devices including any suitable combination of featuresdiscussed with reference to any embodiments discussed herein.

Any suitable principles and advantages of the surface acoustic wavedevices disclosed herein can be implemented with one or more temperaturecompensated SAW resonators. Temperature compensated SAW resonatorsinclude a temperature compensation layer (e.g., a silicon dioxide layer)over an interdigital transducer electrode to bring a temperaturecoefficient of frequency closer to zero.

Packaged surface acoustic wave devices disclosed herein can include oneor more surface acoustic wave resonators included in a filter arrangedto filter a radio frequency signal in a fourth generation (4G) Long TermEvolution (LTE) operating band. Packaged surface acoustic wave devicesdisclosed herein can include one or more surface acoustic waveresonators included in a filter arranged to filter a radio frequencysignal in a fifth generation (5G) New Radio (NR) operating band withinFrequency Range 1 (FR1). FR1 can be from 410 megahertz (MHz) to 7.125gigahertz (GHz), for example, as specified in a current 5G NRspecification. Packaged surface acoustic wave devices disclosed hereincan include one or more surface acoustic wave resonators included in afilter with a passband corresponding to both a 4G LTE operating band anda 5G NR operating band within FR1.

Any of the embodiments described above can be implemented in associationwith a radio frequency system and/or mobile devices such as cellularhandsets. The principles and advantages of the embodiments can be usedfor any systems or apparatus that could benefit from any of theembodiments described herein. The teachings herein are applicable to avariety of systems. Although this disclosure includes exampleembodiments, the teachings described herein can be applied to a varietyof structures. Any of the principles and advantages discussed herein canbe implemented in association with RF circuits configured to processsignals in a frequency range from about 30 kHz to 300 GHz, such as in afrequency range from about 450 MHz to 8.5 GHz.

Aspects of this disclosure can be implemented in various electronicdevices. Examples of the electronic devices can include, but are notlimited to, consumer electronic products, parts of the consumerelectronic products such as semiconductor die and/or packaged radiofrequency modules, electronic test equipment, uplink wirelesscommunication devices, personal area network communication devices, etc.Examples of the consumer electronic products can include, but are notlimited to, a mobile phone such as a smart phone, a wearable computingdevice such as a smart watch or an ear piece, a telephone, a television,a computer monitor, a computer, a router, a modem, a hand-held computer,a laptop computer, a tablet computer, a personal digital assistant(PDA), a microwave, a refrigerator, a vehicular electronics system suchas an automotive electronics system, a stereo system, a DVD player, a CDplayer, a digital music player such as an MP3 player, a radio, acamcorder, a camera such as a digital camera, a portable memory chip, awasher, a dryer, a washer/dryer, a peripheral device, a clock, etc.Further, the electronic devices can include unfinished products.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,”“include,” “including” and the like are to be construed in an inclusivesense, as opposed to an exclusive or exhaustive sense; that is to say,in the sense of “including, but not limited to.” The word “coupled”, asgenerally used herein, refers to two or more elements that may be eitherdirectly connected, or connected by way of one or more intermediateelements. Likewise, the word “connected”, as generally used herein,refers to two or more elements that may be either directly connected, orconnected by way of one or more intermediate elements. Additionally, thewords “herein,” “above,” “below,” and words of similar import, when usedin this application, shall refer to this application as a whole and notto any particular portions of this application. Where the contextpermits, words in the above Detailed Description using the singular orplural number may also include the plural or singular numberrespectively. The word “or” in reference to a list of two or more items,that word covers all of the following interpretations of the word: anyof the items in the list, all of the items in the list, and anycombination of the items in the list.

Moreover, conditional language used herein, such as, among others,“can,” “could,” “might,” “may,” “e.g.,” “for example,” “such as” and thelike, unless specifically stated otherwise, or otherwise understoodwithin the context as used, is generally intended to convey that certainembodiments include, while other embodiments do not include, certainfeatures, elements and/or states. Thus, such conditional language is notgenerally intended to imply that features, elements and/or states are inany way required for one or more embodiments or that one or moreembodiments necessarily include logic for deciding, with or withoutauthor input or prompting, whether these features, elements and/orstates are included or are to be performed in any particular embodiment.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the disclosure. Indeed, the novel apparatus, methods, andsystems described herein may be embodied in a variety of other forms;furthermore, various omissions, substitutions and changes in the form ofthe methods and systems described herein may be made without departingfrom the spirit of the disclosure. For example, while blocks arepresented in a given arrangement, alternative embodiments may performsimilar functionalities with different components and/or circuittopologies, and some blocks may be deleted, moved, added, subdivided,combined, and/or modified. Each of these blocks may be implemented in avariety of different ways. Any suitable combination of the elements andacts of the various embodiments described above can be combined toprovide further embodiments. The accompanying claims and theirequivalents are intended to cover such forms or modifications as wouldfall within the scope and spirit of the disclosure.

What is claimed is:
 1. A packaged surface acoustic wave devicecomprising: a cavity roof over an interdigital transducer electrode of asurface acoustic wave device; a conductive structure over the cavityroof; and a photosensitive buffer coat layer over the conductivestructure, the packaged surface acoustic wave device having a height of220 micrometers or less.
 2. The packaged surface acoustic wave device ofclaim 1 wherein the packaged surface acoustic wave device has a heightof 200 micrometers or less.
 3. The packaged surface acoustic wave deviceof claim 1 wherein the photosensitive buffer coat layer has a height of15 micrometers or less.
 4. The packaged surface acoustic wave device ofclaim 1 further comprising a piezoelectric substrate having a first sideon which the interdigital transducer electrode is disposed, and a cavitywall on the first side of the piezoelectric substrate and supporting thecavity roof.
 5. The packaged surface acoustic wave device of claim 4wherein an edge portion of the first side of the piezoelectric substrateis free from the photosensitive buffer coat layer.
 6. The packagedsurface acoustic wave device of claim 1 further comprising apiezoelectric substrate having a first side and a second side oppositethe first side, the interdigital transducer electrode being on the firstside, and a marking extending into the second side, the markingextending 1 micrometer or less into the piezoelectric substrate.
 7. Thepackaged surface acoustic wave device of claim 1 further comprising aterminal in physical contact with the conductive structure though anopening in the photosensitive buffer coat layer.
 8. The packaged surfaceacoustic wave device of claim 1 wherein the photosensitive buffer coatlayer includes phenol resin.
 9. The packaged surface acoustic wavedevice of claim 1 wherein the photosensitive buffer coat layer has anegative photosensitivity.
 10. The packaged surface acoustic wave deviceof claim 1 wherein the surface acoustic wave device includes a pluralityof surface acoustic wave resonators configured to filter a radiofrequency signal.
 11. A packaged surface acoustic wave devicecomprising: a cavity structure supported by a die and cooperating thedie to encapsulate an interdigital transducer electrode of a surfaceacoustic wave device; a conductive structure extending over a portion ofan outer surface of the cavity structure; and an insulating layerextending over the conductive structure, a portion of the insulatinglayer overlying a portion of the conductive structure having a thicknessof less than 15 micrometers.
 12. The packaged surface acoustic wavedevice of claim 11 wherein the cavity structure includes a cavity wallsupported by a first surface of the die and a cavity roof extending overthe interdigital transducer electrode and supported by the cavity wall.13. The packaged surface acoustic wave device of claim 12 furthercomprising a plurality of terminals, each of the terminals extendingthrough a portion of the insulating layer and contacting a portion ofthe conductive structure.
 14. The packaged surface acoustic wave deviceof claim 11 wherein the insulating layer includes a photoresistmaterial.
 15. The packaged surface acoustic wave device of claim 14wherein the insulating layer includes a negative photoresist.
 16. Thepackaged surface acoustic wave device of claim 14 wherein the diecomprises a laser-marked piezoelectric substrate having a first side anda second side, the first side supporting the cavity structure, thesecond side of the laser-marked piezoelectric substrate having alaser-marked section.
 17. A packaged surface acoustic wave devicecomprising: a piezoelectric substrate; a packaging structure supportedby a first surface of the piezoelectric substrate and defining a cavity,the packaging structure including an outer layer includingphotosensitive resin and a conductive layer at least partially betweenthe cavity and the photosensitive resin; and a plurality of interdigitaltransducer electrodes supported by the piezoelectric substrate andlocated within the cavity, the plurality of interdigital transducerelectrodes including a first interdigital transducer electrode of afirst resonator and a second interdigital transducer electrode of asecond resonator.
 18. The packaged surface acoustic wave device of claim17 wherein the packaging structure includes a cavity roof and a cavitywall, the cavity roof and the cavity wall both located between a portionof the outer layer and the plurality of interdigital transducerelectrodes.
 19. The packaged surface acoustic wave device of claim 17wherein the packaging structure includes a conductive structure havingthe conductive layer in electrical communication with at least one ofthe plurality of interdigital transducer electrodes.
 20. The packagedsurface acoustic wave device of claim 19 wherein the packaging structureincludes at least one terminal overlying a portion of the outer layerand extending through a portion of the outer layer to contact theconductive structure.